Early Triassic

{{Short description|First of three epochs of the Triassic Period}}

{{Infobox geologic timespan

| name = {{Color|White|Early/Lower Triassic}}

| color = Early Triassic

| top_bar =

| time_start = 251.9

| time_start_uncertainty =

| time_end = 246.7

| image_map = Mollweide Paleographic Map of Earth, 250 Ma (Olenekian Age).png

| caption_map = A map of Earth as it appeared 250 million years ago during the Early Triassic Epoch, Olenekian Age

| image_outcrop = Stadtroda Sandstein.jpg

| caption_outcrop = Sandstone from the Lower Triassic Series

| image_art =

| caption_art =

| timeline = Triassic

| partially_contained_in =

| partially_contains =

| chrono_name = Early Triassic

| strat_name = Lower Triassic

| name_formality = Formal

| name_accept_date =

| alternate_spellings =

| synonym1 =

| synonym1_coined =

| synonym2 =

| synonym2_coined =

| synonym3 =

| synonym3_coined =

| nicknames =

| former_names =

| proposed_names =

| celestial_body = earth

| usage = Global (ICS)

| timescales_used = ICS Time Scale

| formerly_used_by =

| not_used_by =

| chrono_unit = Epoch

| strat_unit = Series

| proposed_by =

| timespan_formality = Formal

| lower_boundary_def = FAD of the Conodont Hindeodus parvus

| lower_gssp_location = Meishan, Zhejiang, China

| lower_gssp_coords = {{Coord|31.0798|N|119.7058|E|display=inline}}

| lower_gssp_accept_date = 2001{{cite journal |last1=Hongfu |first1=Yin |last2=Kexin |first2=Zhang |last3=Jinnan |first3=Tong |last4=Zunyi |first4=Yang |last5=Shunbao |first5=Wu |title=The Global Stratotype Section and Point (GSSP) of the Permian-Triassic Boundary |journal=Episodes |date=June 2001 |volume=24 |issue=2 |pages=102–114 |doi=10.18814/epiiugs/2001/v24i2/004 |url=https://stratigraphy.org/gssps/files/induan.pdf |access-date=8 December 2020 |doi-access=free |archive-date=28 August 2021 |archive-url=https://web.archive.org/web/20210828153134/https://stratigraphy.org/gssps/files/induan.pdf |url-status=live }}

| upper_boundary_def = Not formally defined

| upper_def_candidates =

FAD of the Conodont Chiosella timorensis
Base of magnetic zone MT1n

| upper_gssp_candidates =

Desli Caira, Northern Dobruja, Romania
Guandao, Guizhou, China

| o2 =

| co2 =

| temp =

| sea_level =

}}

The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 251.9 Ma and {{Period start|Middle-Triassic}} Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a unit in chronostratigraphy. The Early Triassic is the oldest epoch of the Mesozoic Era. It is preceded by the Lopingian Epoch (late Permian, Paleozoic Era) and followed by the Middle Triassic Epoch. The Early Triassic is divided into the Induan and Olenekian ages. The Induan is subdivided into the Griesbachian and Dienerian subages and the Olenekian is subdivided into the Smithian and Spathian subages.{{cite book |last1=Tozer |first1=Edward T. |title=Lower Triassic stages and ammonoid zones of arctic Canada |date=1965 |publisher=Geological Survey of Canada |oclc=606894884}}

The Lower Triassic series is coeval with the Scythian Stage, which is today not included in the official timescales but can be found in older literature. In Europe, most of the Lower Triassic is composed of Buntsandstein, a lithostratigraphic unit of continental red beds.{{Citation needed|date=February 2024|reason=Citation needed for the entire above section, where none are provided}}

The Early Triassic and partly also the Middle Triassic span the interval of biotic recovery from the Permian-Triassic extinction event, the most severe mass extinction event in Earth's history.{{cite journal |last1=Feng |first1=Xueqian |last2=Chen |first2=Zhong-Qiang |last3=Woods |first3=Adam |last4=Fang |first4=Yuheng |date=15 November 2017 |title=A Smithian (Early Triassic) ichnoassemblage from Lichuan, Hubei Province, South China: Implications for biotic recovery after the latest Permian mass extinction |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018217302420 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=486 |pages=123–141 |doi=10.1016/j.palaeo.2017.03.003 |bibcode=2017PPP...486..123F |access-date=20 January 2023 |archive-date=21 January 2023 |archive-url=https://web.archive.org/web/20230121073305/https://www.sciencedirect.com/science/article/abs/pii/S0031018217302420 |url-status=live |url-access=subscription }}{{cite journal |last1=Matamales-Andreu |first1=Rafel |last2=Peñalver |first2=Enrique |last3=Mujal |first3=Eudald |last4=Oms |first4=Oriol |last5=Scholze |first5=Frank |last6=Juárez |first6=Josep |last7=Galobart |first7=Àngel |last8=Fortuny |first8=Josep |date=November 2021 |title=Early–Middle Triassic fluvial ecosystems of Mallorca (Balearic Islands): Biotic communities and environmental evolution in the equatorial western peri-Tethys |url=https://www.sciencedirect.com/science/article/abs/pii/S0012825221002841 |journal=Earth-Science Reviews |volume=222 |page=103783 |doi=10.1016/j.earscirev.2021.103783 |bibcode=2021ESRv..22203783M |s2cid=238730784 |access-date=8 December 2022 |archive-date=19 December 2022 |archive-url=https://web.archive.org/web/20221219003555/https://www.sciencedirect.com/science/article/abs/pii/S0012825221002841 |url-status=live }} A second extinction event, the Smithian-Spathian boundary event, occurred during the Olenekian.{{cite journal |last1=Widmann |first1=Philipp |last2=Bucher |first2=Hugo |last3=Leu |first3=Marc |last4=Vennemann |first4=Torsten |last5=Bagherpour |first5=Borhan |last6=Schneebeli-Hermann |first6=Elke |last7=Goudemand |first7=Nicolas |last8=Schaltegger |first8=Urs |title=Dynamics of the Largest Carbon Isotope Excursion During the Early Triassic Biotic Recovery |journal=Frontiers in Earth Science |date=2020 |volume=8 |issue=196 |page=196 |doi=10.3389/feart.2020.00196 |bibcode=2020FrEaS...8..196W |doi-access=free}} A third extinction event occurred at the Olenekian-Anisian boundary, marking the end of the Early Triassic epoch.{{cite journal |last1=Song |first1=Haijin |last2=Song |first2=Huyue |last3=Tong |first3=Jinnan |last4=Gordon |first4=Gwyneth W. |last5=Wignall |first5=Paul B. |last6=Tian |first6=Li |last7=Zheng |first7=Wang |last8=Algeo |first8=Thomas J. |last9=Liang |first9=Lei |last10=Bai |first10=Ruoyu |last11=Wu |first11=Kui |last12=Anbar |first12=Ariel D. |date=20 February 2021 |title=Conodont calcium isotopic evidence for multiple shelf acidification events during the Early Triassic |url=https://www.sciencedirect.com/science/article/abs/pii/S0009254120305775 |journal=Chemical Geology |volume=562 |page=120038 |doi=10.1016/j.chemgeo.2020.120038 |bibcode=2021ChGeo.56220038S |s2cid=233915627 |access-date=12 December 2022 |archive-date=12 December 2022 |archive-url=https://web.archive.org/web/20221212003854/https://www.sciencedirect.com/science/article/abs/pii/S0009254120305775 |url-status=live |url-access=subscription }}

Early Triassic climate

File:Тишина озера Дюпкун.jpg is composed of basalt rocks of the Siberian Traps.]]

The climate during the Early Triassic Epoch (especially in the interior of the supercontinent Pangaea) was generally arid, rainless and dry and deserts were widespread; however the poles possessed a temperate climate. The pole-to-equator temperature gradient was temporally flat during the Early Triassic and may have allowed tropical species to extend their distribution poleward. This is evidenced by the global distribution of ammonoids.{{cite journal |last1=Brayard |first1=Arnaud |last2=Bucher |first2=Hugo |last3=Escarguel |first3=Gilles |last4=Fluteau |first4=Frédéric |last5=Bourquin |first5=Sylvie |last6=Galfetti |first6=Thomas |title=The Early Triassic ammonoid recovery: Paleoclimatic significance of diversity gradients |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=September 2006 |volume=239 |issue=3–4 |pages=374–395 |doi=10.1016/j.palaeo.2006.02.003 |bibcode=2006PPP...239..374B}} The extremely hot ocean temperatures facilitated extremely powerful hurricanes that frequently hit the coast of North China.{{Cite journal |last1=Ji |first1=Kaixuan |last2=Wignall |first2=Paul B. |last3=Peakall |first3=Jeff |last4=Tong |first4=Jinnan |last5=Chu |first5=Daoliang |last6=Pruss |first6=Sara B. |date=1 June 2021 |editor-last=Fielding |editor-first=Christopher |title=Unusual intraclast conglomerates in a stormy, hot-house lake: The Early Triassic North China Basin |url=https://onlinelibrary.wiley.com/doi/10.1111/sed.12903 |journal=Sedimentology |language=en |volume=68 |issue=7 |pages=3385–3404 |doi=10.1111/sed.12903 |issn=0037-0746 |access-date=9 March 2024 |via=Wiley Online Library}}

The mostly hot climate of the Early Triassic may have been caused by late volcanic eruptions of the Siberian Traps,{{cite journal |last1=Borruel-Abadía |first1=Violeta |last2=López-Gómez |first2=José |last3=De la Horra |first3=Raúl |last4=Galán-Abellán |first4=Belén |last5=Barrenechea |first5=José |last6=Arche |first6=Alfredo |last7=Ronchi |first7=Ausonio |last8=Gretter |first8=Nicola |last9=Marzo |first9=Mariano |date=15 December 2015 |title=Climate changes during the Early–Middle Triassic transition in the E. Iberian plate and their palaeogeographic significance in the western Tethys continental domain |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018215005532 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=440 |pages=671–689 |doi=10.1016/j.palaeo.2015.09.043 |bibcode=2015PPP...440..671B |access-date=8 December 2022 |archive-date=27 November 2022 |archive-url=https://web.archive.org/web/20221127185642/https://www.sciencedirect.com/science/article/abs/pii/S0031018215005532 |url-status=live |hdl=10261/124328 |hdl-access=free }}{{cite journal |last1=Payne |first1=Jonathan L. |last2=Kump |first2=Lee R. |date=15 April 2007 |title=Evidence for recurrent Early Triassic massive volcanism from quantitative interpretation of carbon isotope fluctuations |url=https://www.sciencedirect.com/science/article/abs/pii/S0012821X07000611 |journal=Earth and Planetary Science Letters |volume=256 |issue=1–2 |pages=264–277 |doi=10.1016/j.epsl.2007.01.034 |bibcode=2007E&PSL.256..264P |access-date=12 January 2023 |archive-date=13 January 2023 |archive-url=https://web.archive.org/web/20230113061729/https://www.sciencedirect.com/science/article/abs/pii/S0012821X07000611 |url-status=live |url-access=subscription }} which had probably triggered the Permian-Triassic extinction event and accelerated the rate of global warming into the Triassic.{{cite journal |last1=Preto |first1=Nereo |last2=Kustatscher |first2=Evelyn |last3=Wignall |first3=Paul B. |title=Triassic climates — State of the art and perspectives |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=April 2010 |volume=290 |issue=1–4 |pages=1–10 |doi=10.1016/j.palaeo.2010.03.015 |bibcode=2010PPP...290....1P}} Studies suggest that Early Triassic climate was very volatile, punctuated by a number of relatively rapid global temperature changes, marine anoxic events, and carbon cycle disturbances,{{cite journal |last1=Schneebeli-Hermann |first1=Elke |date=December 2020 |title=Regime Shifts in an Early Triassic Subtropical Ecosystem |journal=Frontiers in Earth Science |volume=8 |pages=588696 |doi=10.3389/feart.2020.588696 |bibcode=2020FrEaS...8..608S |doi-access=free}}{{cite journal |last1=Li |first1=Hanxiao |last2=Dong |first2=Hanxinshuo |last3=Jiang |first3=Haishui |last4=Wignall |first4=Paul B. |last5=Chen |first5=Yanlong |last6=Zhang |first6=Muhui |last7=Ouyang |first7=Zhumin |last8=Wu |first8=Xianlang |last9=Wu |first9=Baojin |last10=Zhang |first10=Zaitian |last11=Lai |first11=Xulong |date=1 September 2022 |title=Integrated conodont biostratigraphy and δ13Ccarb records from end Permian to Early Triassic at Yiwagou Section, Gansu Province, northwestern China and their implications |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018222002498 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=601 |page=111079 |doi=10.1016/j.palaeo.2022.111079 |bibcode=2022PPP...60111079L |s2cid=249144143 |archive-url=https://web.archive.org/web/20221226222231/https://www.sciencedirect.com/science/article/abs/pii/S0031018222002498 |archive-date=26 December 2022 |access-date=26 December 2022 |url-status=live }}{{cite journal |last1=Lehrmann |first1=Daniel J. |last2=Stepchinski |first2=Leanne |last3=Altiner |first3=Demir |last4=Orchard |first4=Michael J. |last5=Montgomery |first5=Paul |last6=Enos |first6=Paul |last7=Ellwood |first7=Brooks B. |last8=Bowring |first8=Samuel A. |last9=Ramezani |first9=Jahandar |last10=Wang |first10=Hongmei |last11=Wei |first11=Jiayong |last12=Yu |first12=Meiyi |last13=Griffiths |first13=James W. |last14=Minzoni |first14=Marcello |last15=Schaal |first15=Ellen K. |last16=Li |first16=Xiaowei |last17=Meyer |first17=Katja M. |last18=Payne |first18=Jonathan L. |date=15 August 2015 |title=An integrated biostratigraphy (conodonts and foraminifers) and chronostratigraphy (paleomagnetic reversals, magnetic susceptibility, elemental chemistry, carbon isotopes and geochronology) for the Permian–Upper Triassic strata of Guandao section, Nanpanjiang Basin, south China |journal=Journal of Asian Earth Sciences |volume=108 |pages=117–135 |doi=10.1016/j.jseaes.2015.04.030 |bibcode=2015JAESc.108..117L |doi-access=free }} which led to subsequent extinction events in the aftermath of the Permian-Triassic extinction event.{{cite journal |last1=Romano |first1=Carlo |last2=Goudemand |first2=Nicolas |last3=Vennemann |first3=Torsten W. |last4=Ware |first4=David |last5=Schneebeli-Hermann |first5=Elke |last6=Hochuli |first6=Peter A. |last7=Brühwiler |first7=Thomas |last8=Brinkmann |first8=Winand |last9=Bucher |first9=Hugo |title=Climatic and biotic upheavals following the end-Permian mass extinction |journal=Nature Geoscience |date=21 December 2012 |volume=6 |issue=1 |pages=57–60 |doi=10.1038/ngeo1667 |s2cid=129296231}}{{cite journal |last1=Sun |first1=Y. |last2=Joachimski |first2=M. M. |last3=Wignall |first3=P. B. |last4=Yan |first4=C. |last5=Chen |first5=Y. |last6=Jiang |first6=H. |last7=Wang |first7=L. |last8=Lai |first8=X. |title=Lethally Hot Temperatures During the Early Triassic Greenhouse |journal=Science |date=18 October 2012 |volume=338 |issue=6105 |pages=366–370 |doi=10.1126/science.1224126 |pmid=23087244 |bibcode=2012Sci...338..366S |s2cid=41302171}}{{cite journal |last1=Goudemand |first1=Nicolas |last2=Romano |first2=Carlo |last3=Leu |first3=Marc |last4=Bucher |first4=Hugo |last5=Trotter |first5=Julie A. |last6=Williams |first6=Ian S. |title=Dynamic interplay between climate and marine biodiversity upheavals during the early Triassic Smithian -Spathian biotic crisis |journal=Earth-Science Reviews |date=August 2019 |volume=195 |pages=169–178 |doi=10.1016/j.earscirev.2019.01.013 |bibcode=2019ESRv..195..169G |doi-access=free}} On the other hand, an alternative hypothesis proposes these Early Triassic climatic perturbations and biotic upheavals that inhibited the recovery of life following the P-T mass extinction to have been linked to forcing driven by changes in the Earth's obliquity defined by a roughly 32.8 thousand year periodicity with strong 1.2 million year modulations. According to proponents of this hypothesis, radiometric dating indicates that major activity from the Siberian Traps ended very shortly after the end-Permian extinction and did not span the entire Early Triassic epoch, thus not being the primary culprit for the climatic changes throughout this epoch.{{cite journal |last1=Li |first1=Mingsong |last2=Huang |first2=Chunju |last3=Hinnov |first3=Linda |last4=Ogg |first4=James |last5=Chen |first5=Zhong-Qiang |last6=Zhang |first6=Yang |date=1 August 2016 |title=Obliquity-forced climate during the Early Triassic hothouse in China |url=https://pubs.geoscienceworld.org/gsa/geology/article-abstract/44/8/623/188194/Obliquity-forced-climate-during-the-Early-Triassic |journal=Geology |volume=44 |issue=8 |pages=623–626 |doi=10.1130/G37970.1 |bibcode=2016Geo....44..623L |access-date=8 December 2022 |archive-date=30 August 2022 |archive-url=https://web.archive.org/web/20220830062747/https://pubs.geoscienceworld.org/gsa/geology/article-abstract/44/8/623/188194/Obliquity-forced-climate-during-the-Early-Triassic |url-status=live |url-access=subscription }}

Early Triassic life

=Fauna and flora=

File:Pleuromeia restoration.png represented a dominant element of global floras during the Early Triassic]]

The Triassic Period opened in the aftermath of the Permian–Triassic extinction event. The massive extinctions that ended the Permian Period (and with that the Paleozoic Era) caused extreme hardships for the surviving species.

The Early Triassic Epoch saw the biotic recovery of life after the biggest mass extinction event of the past, which took millions of years due to the severity of the event and the harsh Early Triassic climate.{{cite journal |last1=Chen |first1=Zhong-Qiang |last2=Benton |first2=Michael J. |title=The timing and pattern of biotic recovery following the end-Permian mass extinction |journal=Nature Geoscience |date=27 May 2012 |volume=5 |issue=6 |pages=375–383 |doi=10.1038/ngeo1475 |bibcode=2012NatGe...5..375C}} Many types of corals, brachiopods, molluscs, echinoderms, and other invertebrates had disappeared. The Permian vegetation, which was dominated by Glossopteris in the Southern Hemisphere, ceased to exist.{{cite journal |last1=Hochuli |first1=Peter A. |last2=Sanson-Barrera |first2=Anna |last3=Schneebeli-Hermann |first3=Elke |last4=Bucher |first4=Hugo |title=Severest crisis overlooked—Worst disruption of terrestrial environments postdates the Permian–Triassic mass extinction |journal=Scientific Reports |date=24 June 2016 |volume=6 |issue=1 |pages=28372 |doi=10.1038/srep28372 |pmid=27340926 |pmc=4920029 |bibcode=2016NatSR...628372H}} Other groups, such as Actinopterygii, appear to have been less affected by this extinction event{{cite journal |last1=Smithwick |first1=Fiann M. |last2=Stubbs |first2=Thomas L. |title=Phanerozoic survivors: Actinopterygian evolution through the Permo-Triassic and Triassic-Jurassic mass extinction events |journal=Evolution |date=2 February 2018 |volume=72 |issue=2 |pages=348–362 |doi=10.1111/evo.13421 |pmid=29315531 |pmc=5817399 |doi-access=free}} and body size was not a selective factor during the extinction event.{{cite journal |last1=Romano |first1=Carlo |last2=Koot |first2=Martha B. |last3=Kogan |first3=Ilja |last4=Brayard |first4=Arnaud |last5=Minikh |first5=Alla V. |last6=Brinkmann |first6=Winand |last7=Bucher |first7=Hugo |last8=Kriwet |first8=Jürgen |title=Permian-Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolution |journal=Biological Reviews |date=February 2016 |volume=91 |issue=1 |pages=106–147 |doi=10.1111/brv.12161 |pmid=25431138 |s2cid=5332637}}{{cite journal |last1=Puttick |first1=Mark N. |last2=Kriwet |first2=Jürgen |last3=Wen |first3=Wen |last4=Hu |first4=Shixue |last5=Thomas |first5=Gavin H. |last6=Benton |first6=Michael J. |last7=Angielczyk |first7=Kenneth |title=Body length of bony fishes was not a selective factor during the biggest mass extinction of all time |journal=Palaeontology |date=September 2017 |volume=60 |issue=5 |pages=727–741 |doi=10.1111/pala.12309 |bibcode=2017Palgy..60..727P |doi-access=free|hdl=1983/bda1adfa-7dd7-41e3-accf-a93d9d034518 |hdl-access=free }} Animals that were most successful in the Early Triassic were those with high metabolisms.{{cite journal |last1=Pietsch |first1=Carlie |last2=Ritterbush |first2=Kathleen A. |last3=Thompson |first3=Jeffrey R. |last4=Petsios |first4=Elizabeth |last5=Bottjer |first5=David J. |date=1 January 2019 |title=Evolutionary models in the Early Triassic marine realm |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018217305965 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=513 |pages=65–85 |doi=10.1016/j.palaeo.2017.12.016 |bibcode=2019PPP...513...65P |s2cid=134281291 |access-date=3 December 2022 |archive-date=2 December 2022 |archive-url=https://web.archive.org/web/20221202231252/https://www.sciencedirect.com/science/article/abs/pii/S0031018217305965 |url-status=live |url-access=subscription }} Different patterns of recovery are evident on land and in the sea. Early Triassic faunas lacked biodiversity and were relatively homogeneous due to the effects of the extinction. The ecological recovery on land took 30 million years, well into the Late Triassic.{{cite journal |last1=Sahney |first1=Sarda |last2=Benton |first2=Michael J |title=Recovery from the most profound mass extinction of all time |journal=Proceedings of the Royal Society B: Biological Sciences |date=15 January 2008 |volume=275 |issue=1636 |pages=759–765 |doi=10.1098/rspb.2007.1370 |pmid=18198148 |pmc=2596898}} Two Early Triassic lagerstätten stand out due to their exceptionally high biodiversity, the Dienerian aged Guiyang biota{{cite journal |last1=Dai |first1=Xu |last2=Davies |first2=Joshua H.F.L. |last3=Yuan |first3=Zhiwei |last4=Brayard |first4=Arnaud |last5=Ovtcharova |first5=Maria |last6=Xu |first6=Guanghui |last7=Liu |first7=Xiaokang |last8=Smith |first8=Christopher P.A. |last9=Schweitzer |first9=Carrie E. |last10=Li |first10=Mingtao |last11=Perrot |first11=Morgann G. |last12=Jiang |first12=Shouyi |last13=Miao |first13=Luyi |last14=Cao |first14=Yiran |last15=Yan |first15=Jia |last16=Bai |first16=Ruoyu |last17=Wang |first17=Fengyu |last18=Guo |first18=Wei |last19=Song |first19=Huyue |last20=Tian |first20=Li |last21=Dal Corso |first21=Jacopo |last22=Liu |first22=Yuting |last23=Chu |first23=Daoliang |last24=Song |first24=Haijun |year=2023 |title=A Mesozoic fossil lagerstätte from 250.8 million years ago shows a modern-type marine ecosystem |journal=Science |volume=379 |issue=6632 |pages=567–572 |doi=10.1126/science.adf1622|pmid=36758082 |bibcode=2023Sci...379..567D |s2cid=256697946 }} and the earliest Spathian aged Paris biota.{{cite journal |last1=Brayard |first1=Arnaud |last2=Krumenacker |first2=L. J. |last3=Botting |first3=Joseph P. |last4=Jenks |first4=James F. |last5=Bylund |first5=Kevin G. |last6=Fara |first6=Emmanuel |last7=Vennin |first7=Emmanuelle |last8=Olivier |first8=Nicolas |last9=Goudemand |first9=Nicolas |last10=Saucède |first10=Thomas |last11=Charbonnier |first11=Sylvain |last12=Romano |first12=Carlo |last13=Doguzhaeva |first13=Larisa |last14=Thuy |first14=Ben |last15=Hautmann |first15=Michael |last16=Stephen |first16=Daniel A. |last17=Thomazo |first17=Christophe |last18=Escarguel |first18=Gilles |title=Unexpected Early Triassic marine ecosystem and the rise of the Modern evolutionary fauna |journal=Science Advances |year=2017 |volume=3 |issue=2 |pages=e1602159 |doi=10.1126/sciadv.1602159 |pmid=28246643 |pmc=5310825 |bibcode=2017SciA....3E2159B |doi-access=free }}

==Terrestrial biota==

The most common land vertebrate was the small herbivorous synapsid Lystrosaurus. Often interpreted as a disaster taxon (although this view was questioned{{cite journal |last1=Modesto |first1=Sean P. |title=The Disaster Taxon Lystrosaurus: A Paleontological Myth |journal=Frontiers in Earth Science |date=December 2020 |volume=8 |pages=610463 |doi=10.3389/feart.2020.610463 |bibcode=2020FrEaS...8..617M |doi-access=free}}), Lystrosaurus had a wide range across Pangea. In the southern part of the supercontinent, it co-occurred with the non-mammalian cynodonts Galesaurus and Thrinaxodon, early relatives of mammals. The first archosauriforms appeared, such as Erythrosuchus (Olenekian-Ladinian).{{cite journal |last1=Foth |first1=Christian |last2=Ezcurra |first2=Martín D. |last3=Sookias |first3=Roland B. |last4=Brusatte |first4=Stephen L. |last5=Butler |first5=Richard J. |title=Unappreciated diversification of stem archosaurs during the Middle Triassic predated the dominance of dinosaurs |journal=BMC Evolutionary Biology |date=15 September 2016 |volume=16 |issue=1 |page=188 |doi=10.1186/s12862-016-0761-6 |pmid=27628503 |pmc=5024528 |doi-access=free}} This group includes the ancestors of crocodiles and dinosaurs (including birds). Fossilized foot prints of dinosauromorphs are known from the Olenekian.{{cite journal |last1=Brusatte |first1=Stephen L. |last2=Niedźwiedzki |first2=Grzegorz |last3=Butler |first3=Richard J. |title=Footprints pull origin and diversification of dinosaur stem lineage deep into Early Triassic |journal=Proceedings of the Royal Society B: Biological Sciences |date=6 October 2010 |volume=278 |issue=1708 |pages=1107–1113 |doi=10.1098/rspb.2010.1746 |pmid=20926435 |pmc=3049033 |doi-access=free}} The Early Triassic entomofauna is very poorly understood because of the paucity of insect fossils from this epoch.{{Cite journal |last1=Żyła |first1=Dagmara |last2=Wegierek |first2=Piotr |last3=Owocki |first3=Krzysztof |last4=Niedźwiedzki |first4=Grzegorz |date=1 February 2013 |title=Insects and crustaceans from the latest Early–early Middle Triassic of Poland |url=https://www.sciencedirect.com/science/article/pii/S0031018213000060 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=371 |pages=136–144 |doi=10.1016/j.palaeo.2013.01.002 |issn=0031-0182 |access-date=8 December 2023|url-access=subscription }}

The flora was gymnosperm-dominated at the onset of the Triassic, but changed rapidly and became lycopod-dominated (e.g. Pleuromeia) during the Griesbachian-Dienerian ecological crisis. This change coincided with the extinction of the Permian Glossopteris flora. In the Spathian subage, the flora changed back to gymnosperm and pteridophyte dominated.{{cite journal |last1=Schneebeli-Hermann |first1=Elke |last2=Kürschner |first2=Wolfram M. |last3=Kerp |first3=Hans |last4=Bomfleur |first4=Benjamin |last5=Hochuli |first5=Peter A. |last6=Bucher |first6=Hugo |last7=Ware |first7=David |last8=Roohi |first8=Ghazala |title=Vegetation history across the Permian–Triassic boundary in Pakistan (Amb section, Salt Range) |journal=Gondwana Research |date=April 2015 |volume=27 |issue=3 |pages=911–924 |doi=10.1016/j.gr.2013.11.007 |bibcode=2015GondR..27..911S}} These shifts reflect global changes in precipitation and temperature. Floral diversity was overall very low during the Early Triassic, as plant life had yet to fully recover from the Permian-Triassic extinction.{{cite journal |last1=Xu |first1=Zhen |last2=Hilton |first2=Jason |last3=Yu |first3=Jianxin |last4=Wignall |first4=Paul B. |last5=Yin |first5=Hongfu |last6=Xue |first6=Qing |last7=Ran |first7=Weiju |last8=Li |first8=Hui |last9=Shen |first9=Jun |last10=Meng |first10=Fansong |date=22 July 2022 |title=End Permian to Middle Triassic plant species richness and abundance patterns in South China: Coevolution of plants and the environment through the Permian–Triassic transition |url=https://www.sciencedirect.com/science/article/abs/pii/S0012825222002203 |url-status=bot: unknown |journal=Earth-Science Reviews |volume=232 |page=104136 |bibcode=2022ESRv..23204136X |doi=10.1016/j.earscirev.2022.104136 |s2cid=251031028 |archive-url=https://web.archive.org/web/20221128061610/https://www.sciencedirect.com/science/article/abs/pii/S0012825222002203 |archive-date=28 November 2022 |access-date= }}

Microbially induced sedimentary structures (MISS) are common in the fossil record of North China in the immediate aftermath of the Permian-Triassic extinction, indicating that microbial mats dominated local terrestrial ecosystems following the Permian-Triassic boundary. The regional prevalence of MISS is attributable to a decrease in bioturbation and grazing pressure as a result of aridification and temperature increase. MISS have also been reported from Early Triassic fossil deposits in Arctic Canada.{{cite journal |last1=Wignall |first1=Paul B. |last2=Bond |first2=David P. G. |last3=Grasby |first3=Stephen E. |last4=Pruss |first4=Sarah B. |last5=Peakall |first5=Jeffrey |date=30 August 2019 |title=Controls on the formation of microbially induced sedimentary structures and biotic recovery in the Lower Triassic of Arctic Canada |journal=Geological Society of America Bulletin |volume=132 |issue=5–6 |pages=918–930 |doi=10.1130/B35229.1 |s2cid=202194000 |doi-access=free }} The disappearance of MISS later in the Early Triassic has been interpreted as a signal of increased bioturbation and recovery of terrestrial ecosystems.{{cite journal |last1=Chu |first1=Daoliang |last2=Tong |first2=Jinnan |last3=Bottjer |first3=David J. |last4=Song |first4=Haijun |last5=Song |first5=Huyue |last6=Benton |first6=Michael James |last7=Tian |first7=Li |last8=Guo |first8=Wenwei |date=15 May 2017 |title=Microbial mats in the terrestrial Lower Triassic of North China and implications for the Permian–Triassic mass extinction |url=https://www.sciencedirect.com/science/article/abs/pii/S003101821630205X |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=474 |pages=214–231 |doi=10.1016/j.palaeo.2016.06.013 |bibcode=2017PPP...474..214C |hdl=1983/95966174-157e-4814-b73f-6901ff9b9bf8 |access-date=23 December 2022 |archive-date=24 December 2022 |archive-url=https://web.archive.org/web/20221224043223/https://www.sciencedirect.com/science/article/abs/pii/S003101821630205X |url-status=live |hdl-access=free }}

==Aquatic biota==

In the oceans, the most common Early Triassic hard-shelled marine invertebrates were bivalves, gastropods, ammonoids, echinoids, and a few articulate brachiopods. Conodonts experienced a revival in diversity following a nadir during the Permian.{{Cite journal |last1=Ginot |first1=Samuel |last2=Goudemand |first2=Nicolas |date=December 2020 |title=Global climate changes account for the main trends of conodont diversity but not for their final demise |journal=Global and Planetary Change |language=en |volume=195 |pages=103325 |doi=10.1016/j.gloplacha.2020.103325 |bibcode=2020GPC...19503325G |s2cid=225005180 |doi-access=free}} The first oysters (Liostrea) appeared in the Early Triassic. They grew on the shells of living ammonoids as epizoans.{{cite journal |last1=Hautmann |first1=Michael |last2=Ware |first2=David |last3=Bucher |first3=Hugo |title=Geologically oldest oysters were epizoans on Early Triassic ammonoids |journal=Journal of Molluscan Studies |date=August 2017 |volume=83 |issue=3 |pages=253–260 |doi=10.1093/mollus/eyx018 |doi-access=free}} Microbial reefs were common, possibly due to lack of competition with metazoan reef builders as a result of the extinction.{{cite journal |last1=Foster |first1=William J. |last2=Heindel |first2=Katrin |last3=Richoz |first3=Sylvain |last4=Gliwa |first4=Jana |last5=Lehrmann |first5=Daniel J. |last6=Baud |first6=Aymon |last7=Kolar-Jurkovšek |first7=Tea |last8=Aljinović |first8=Dunja |last9=Jurkovšek |first9=Bogdan |last10=Korn |first10=Dieter |last11=Martindale |first11=Rowan C. |last12=Peckmann |first12=Jörn |title=Suppressed competitive exclusion enabled the proliferation of Permian/Triassic boundary microbialites |journal=The Depositional Record |date=20 November 2019 |volume=6 |issue=1 |pages=62–74 |doi=10.1002/dep2.97 |pmid=32140241 |pmc=7043383 |doi-access=free}} However, transient metazoan reefs reoccurred during the Olenekian wherever permitted by environmental conditions.{{cite journal |last1=Brayard |first1=Arnaud |last2=Vennin |first2=Emmanuelle |last3=Olivier |first3=Nicolas |last4=Bylund |first4=Kevin G. |last5=Jenks |first5=Jim |last6=Stephen |first6=Daniel A. |last7=Bucher |first7=Hugo |last8=Hofmann |first8=Richard |last9=Goudemand |first9=Nicolas |last10=Escarguel |first10=Gilles |title=Transient metazoan reefs in the aftermath of the end-Permian mass extinction |journal=Nature Geoscience |date=18 September 2011 |volume=4 |issue=10 |pages=693–697 |doi=10.1038/ngeo1264 |bibcode=2011NatGe...4..693B}} Ammonoids show blooms followed by extinctions during the Early Triassic.{{cite journal |last1=Brayard |first1=A. |last2=Escarguel |first2=G. |last3=Bucher |first3=H. |last4=Monnet |first4=C. |last5=Bruhwiler |first5=T. |last6=Goudemand |first6=N. |last7=Galfetti |first7=T. |last8=Guex |first8=J. |title=Good Genes and Good Luck: Ammonoid Diversity and the End-Permian Mass Extinction |journal=Science |date=27 August 2009 |volume=325 |issue=5944 |pages=1118–1121 |doi=10.1126/science.1174638 |pmid=19713525 |bibcode=2009Sci...325.1118B |s2cid=1287762}}

Aquatic vertebrates diversified after the extinction:

Fishes: Many species of fish had a worldwide distribution during the Early Triassic. Typical Triassic ray-finned fishes, such as Australosomus, Birgeria, Bobasatrania, Boreosomus, Pteronisculus, Parasemionotidae and Saurichthys appeared close to the Permian-Triassic boundary, whereas neopterygians (including stem teleosts) diversified later during the Triassic, though the pattern of the Triassic diversification of bony fishes is not well understood due to a taphonomic megabias (Spathian-Bithynian Gap, SBG) in the late Early Triassic and early Middle Triassic.{{cite journal |last1=Romano |first1=Carlo |title=A hiatus obscures the early evolution of Modern lineages of bony fishes |journal=Frontiers in Earth Science |date=January 2021 |volume=8 |pages=618853 |doi=10.3389/feart.2020.618853 |doi-access=free}} The earliest large durophagous neopterygian is known from this gap,{{Cite journal|last1=Cavin |first1=L. |last2=Argyriou |first2=T. |last3=Romano |first3=C. |last4=Grădinaru |first4=E. |year=2024 |title=Large durophagous fish from the Spathian (late Early Triassic) of Romania hints at earlier onset of the Triassic actinopterygian revolution |journal=Papers in Palaeontology |volume=10 |issue=2 |at=e1553 |doi=10.1002/spp2.1553 }} suggesting an early onset in feeding specializations of this group. Most bony fish reached large body sizes during the Early Triassic. Coelacanths show a peak in their diversity during this epoch,{{cite journal |last1=Cavin |first1=Lionel |last2=Furrer |first2=Heinz |last3=Obrist |first3=Christian |year=2013 |title=New coelacanth material from the Middle Triassic of eastern Switzerland, and comments on the taxic diversity of actinistans |journal=Swiss Journal of Geoscience |volume=106 |issue=2 |pages=161–177 |doi=10.1007/s00015-013-0143-7 |doi-access=free}} including new modes of life, such as the fork-tailed Rebellatrix.{{Cite journal |last1=Wendruff |first1=A. J. |last2=Wilson |first2=M. V. H. |year=2012 |title=A fork-tailed coelacanth, Rebellatrix divaricerca, gen. et sp. nov. (Actinistia, Rebellatricidae, fam. nov.), from the Lower Triassic of Western Canada |url=https://www.academia.edu/3197708 |journal=Journal of Vertebrate Paleontology |volume=32 |issue=3 |pages=499–511 |doi=10.1080/02724634.2012.657317 |bibcode=2012JVPal..32..499W |s2cid=85826893}} Chondrichthyes are represented by Hybodontiformes like Palaeobates, Omanoselache, Lissodus, some Neoselachii, as well as a few last survivors of the Eugeneodontida (Caseodus, Fadenia).{{cite book |last1=Mutter |first1=Raoul J. |last2=Neuman |first2=Andrew G. |year=2008 |chapter=New eugeneodontid sharks from the Lower Triassic Sulphur Mountain Formation of Western Canada |title=Fishes and the Break-up of Pangaea |url=https://doi.org/10.1144/SP295.3 |editor1=Cavin, L. |editor2=Longbottom, A. |editor3=Richter, M. |series=Geological Society of London, Special Publications |publisher=Geological Society of London |location=London |volume=295 |pages=9–41 |doi=10.1144/sp295.3|s2cid=130268582 }}

Amphibians: Relatively large, marine temnospondyl amphibians, such as Aphaneramma or Wantzosaurus, were geographically widespread during the Induan and Olenekian ages. The fossils of these crocodile-shaped amphibians were found in Greenland, Spitsbergen, Pakistan and Madagascar.{{Citation needed|date=February 2024|reason=Citation needed for the entire above section, where none are provided}}

Reptiles: In the oceans, the first marine reptiles appeared during the Early Triassic.{{cite journal |last1=Scheyer |first1=Torsten M. |last2=Romano |first2=Carlo |last3=Jenks |first3=Jim |last4=Bucher |first4=Hugo |title=Early Triassic Marine Biotic Recovery: The Predators' Perspective |journal=PLOS ONE |date=19 March 2014 |volume=9 |issue=3 |pages=e88987 |doi=10.1371/journal.pone.0088987 |pmid=24647136 |pmc=3960099 |bibcode=2014PLoSO...988987S |doi-access=free}} Their descendants ruled the oceans during the Mesozoic. Hupehsuchia, Ichthyopterygia and sauropterygians are among the first marine reptiles to enter the scene in the Olenekian (e.g. Cartorhynchus, Chaohusaurus, Utatsusaurus, Hupehsuchus, Grippia, Omphalosaurus, Corosaurus). Other marine reptiles such as Tanystropheus, Helveticosaurus, Atopodentatus, placodonts or the thalattosaurs followed later in the Middle Triassic. The Anisian aged ichthyosaur Thalattoarchon was one of the first marine macropredators capable of eating prey that was similar in size to itself, an ecological role that can be compared to that of modern orcas.{{cite journal |last1=Fröbisch |first1=Nadia B. |last2=Fröbisch |first2=Jörg |last3=Sander |first3=P. Martin |last4=Schmitz |first4=Lars |last5=Rieppel |first5=Olivier |title=Macropredatory ichthyosaur from the Middle Triassic and the origin of modern trophic networks |journal=Proceedings of the National Academy of Sciences |date=22 January 2013 |volume=110 |issue=4 |pages=1393–1397 |doi=10.1073/pnas.1216750110 |pmid=23297200 |pmc=3557033 |bibcode=2013PNAS..110.1393F |doi-access=free}}

=Fossil gallery=

File:PMS - spodnjetriasni kačjerepi (Ophiuroidea).jpg|Early Triassic brittle stars (echinoderms)

File:Claraia Clarai Museum Gröden.jpg|Fossils of the bivalve Claraia clarai

File:Hedenstroemiidae_-_Hedenstroemia_tscherskii.JPG|Early Triassic ammonoid Hedenstroemia

File:Candelarialepis argentus.png|Fossil of the Early Triassic neopterygian Candelarialepis argentus

File:HupehsuchusNanchangensis-PaleozoologicalMuseumOfChina-May23-08.jpg|Early Triassic Hupehsuchus fossil in the Paleozoological Museum of China

File:Erythrosuchus africanus 34.jpg|Skull of the Early Triassic archosauriform Erythrosuchus

File:Lystrosaurus hedini.JPG|Lystrosaurus hedini skeleton at the Museum of Paleontology in Tübingen

References

External links

[http://www.stratigraphy.org/bak/geowhen/stages/Early_Triassic.html GeoWhen Database – Early Triassic]
[https://web.archive.org/web/20060102032421/http://www.palaeos.com/Mesozoic/Triassic/EarlyTrias.htm Palaeos] (archived 2 January 2006)
[http://www.scotese.com/etriascl.htm scotese]

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Category:Geological epochs

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de:Buntsandstein